Conventionally, an extrusion method is generally used for granulating powder having the strong adhesion. However, when using said method, it is necessary to perform unit operations such as mixing of powder with a binding material, kneading, granulation, conglobation and the like independently. As a result, the number of processes is increased and it takes much time to carry out such processes, and therefore, there is a drawback that the manufacturing cost is increased.
For example, Japanese Laid-Open Publication No. 2000-354753 discloses a mixing and granulating machine comprising: a container 55 containing powder; a rotating blade 56, which rotates at the bottom portion of the container to revolve and flow the powder; and a crushing blade 57, which rotates in the revolving and flowing powder to shear it, wherein the crushing blade 57 is revolved along the inner circumferential surface of the container 55, in order to carry out mixing of the powder, agitating thereof and the like in one step, as shown in FIG. 10.
In this mixing and granulating machine, the rotating blade 56 has a shape by which the powder is kicked up when the rotating blade 56 rotates. A raw powder charged in the container 55 is kicked up by the rotating blade 56 and is convected. In the convection current of the powder, a binding agent is added dropwise or sprayed from a nozzle 58, and the crushing blade 57 shears the granulated material in the convection current to prevent segregation and the like.
Thus, though a conventional mixing and granulating machine can kick up and shear powder at the time of granulation, kneading actions are not sufficiently provided, and therefore, it is difficult to adjust strength and an elution state of a granulated material. Further, since the adhesion of a material to the container is significantly high, it takes time to remove the material therefrom, and as a result, the productivity is decreased. Furthermore, there is a drawback that particles (granulated material) are not formed when a hardly-soluble (slightly soluble) drug is contained.
Japanese Utility Model Registration No. 2521765 discloses a mixing and granulating machine, wherein: a lower blade and an upper blade are rotatably arranged in a tank; the lower blade is arranged to provide a narrow gap between itself and the bottom of the tank; a material to be treated in a tank is lifted up and moved toward the center of the tank by the lower blade; and the material to be treated is given the shearing force by the upper blade, which rotates at a high speed, and is mixed at the same time to be granulated.
Further, Japanese Publication for Opposition No. 6-24619 discloses a granulating machine comprising: a tubular container; a low speed rotor equipped with a mixing member in proximity to the inner circumferential surface of the container; and two high speed rotors comprising many impact members.
However, similarly, in these mixing and granulating machines, kneading actions are not sufficiently provided, and therefore, it is difficult to adjust strength and an elution state of a granulated material. Further, since the adhesion of a material to the container is significantly high, it takes time to remove the material therefrom, and as a result, the productivity is decreased.